Basket jig for electroless plating apparatus and electroless plating method

ABSTRACT

The present invention relates to a basket jig for an electroless plating apparatus and an electroless plating method. A basket jig for an electroless plating apparatus in accordance with the present invention includes a basket loaded thereon a plurality of printed circuit boards, a rotating structure coupled to top portions of both sides of the basket and a tube in a shape of a rectangular plate coupled to bottom portions of the basket.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. Section 119 of Korean Patent Application Serial No. 10-2012-0111693, filed Oct. 9, 2012, which is hereby incorporated by reference in its entirety into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a basket jig for an electroless plating apparatus and an electroless plating method, and more particularly, to a basket jig for an electroless plating apparatus capable of improving a plating quality by rotating the basket in the plating bath due to a buoyancy and a self-weight.

2. Description of the Related Art

Generally, a printed circuit board (PCB) plays a role of electrically connecting a plurality of devices of electronic products and as a component is widely used from a home appliance such as a digital TV to a high-tech communication device, it can be classified by a universal PCB, a PCB for a module, a PCB for a package or the like according to usage.

As the PCB is formed by attaching a thin film such as a copper to one side of a phenol resin insulating plate or an epoxy resin insulating plate or the like, forming a required circuit by etching along with a wiring pattern of the following circuit (removing by etching with remaining only the circuit on the line) and forming by penetrating holes to attach and mount components, it can be classified into a single side substrate, a double side substrate, a multi-layer substrate or the like according to the number of the wiring circuit surfaces; as greater the number of layers, the mounting capability of components is excellent; and, accordingly, an ultra thin film PCB, e.g., a thickness ranging from 0.04 mm to 0.2 mm, has been widely used recently due to the development of electronics industry.

A conventional electroless plating mainly utilizes a method, after performing processes to insert the PCB into a basket slot and load a plurality of PCBs and for fixing with a fixing clamp, to plate copper (Cu), nickel (Ni), palladium (Pd), gold (Ag), tin (Sn) or the like on the surface of the PCB under the condition that the basket is deposited by inserting the basket loaded therein the PCBs into the plating bath where the plating solution exists.

When the basket is immerged into the plating bath, a bottom portion of the basket reaches the plating solution first; and, when it is extracted from the plating bath, the bottom portion is get out from the plating solution at the latest time.

In general, since the time consumed for immerging the basket into the plating bath and the time consumed for extracting the basket are approximately 20 seconds totally which is shorter than a whole time in comparison with a total plating time, e.g., approximately 15 minutes or 20 minutes, consumed from immerging the basket until extracting the basket, it does not have influence to make a thickness deviation, thereby sufficiently disregarding the time consumed for immerging and extracting the basket.

However, in case when the thickness is ranging from 0.1 μm to 1 μm as an ultra thin film, since the time consumed for the total plating time is below 1 minute, the occupied ratio of the time consumed from immerging the basket until extracting the basket to the total plating time consumed from immerging the basket until extracting the basket is very larger than (the maximum is approximately 20%), the time to immerge the basket into the plating bath and the time to extract the basket from the plating bath become a main factor to generate the difference of plating thickness at the top portion and the bottom portion of the printed circuit board; and, more particularly, there is a problem the plating thickness of the bottom portion of the substrate is thicker than that of the top portion of the substrate.

And also, although the stirring of the plating solution is applied by using an apparatus for uniformizing the plating in the plating bath (using a bubble formation, a mechanical apparatus or the like by using an air pump), there is a limitation to minimize the generation of the plating thickness deviation.

[Related Art Document]

[Patent Document]

Patent Document 1: Japanese Patent Laid-open Publication No. 2004-300462

Patent Document 2: Japanese Patent Laid-open Publication No. 2011-231347

SUMMARY OF THE INVENTION

The present invention has been invented in order to overcome the above-described problems and it is, therefore, an object of the present invention to provide a basket jig for an electroless plating apparatus consisting of a basket loaded thereon a plurality of printed circuit board, a rotating structure coupled to top portions of both side surfaces of the basket and a tube connected to a bottom of the basket to generate a buoyancy .

In accordance with a first embodiment of the present invention to achieve the object, there is provided a basket jig for an electroless plating apparatus including a basket loaded thereon a plurality of printed circuit boards, a rotating structure coupled to top portions of both sides of the basket; and a tube in a shape of a rectangular plate coupled to bottom portions of the basket.

At this time, the rotating structure includes a carrier to move up and down, a bearing placed in a bottom portion and a rotating axis coupled to the bearing of which end portions are connected to the basket.

Further, the tube is divided in such a way that materials having different densities from each other are arranged on a front part and a rear part.

Further, the tube has a side surface in a shape of a trapezoid or a triangle as a structure to have a long front part and a short rear part.

Further, a point is formed on the tube to be separated from a bottom front part of the basket at a predetermined interval.

Further, the tube is made of a corrosion resistant material capable of protecting the corrosion from a plating solution.

Further, the tube is made of a material with a density lower than that of the plating solution.

Further, the tube is made of a material selected from a group consisting of polytetrafluoreethylene (PTFE), polyvinyl chloride (PVC), polypropylene, fiberglass-reinforced plastics, polyethylene, furan, epoxy, polyester, vinyl ester, urethane, natural rubber, neporpene, butyl rubber, chlorobutyl rubber, chlorosulfonated polyethylene (CSPE), fluororcarbons or the like.

On the other hands, in accordance with a second embodiment of the present invention to achieve the object, there is provided an electroless plating method including placing a basket jig for an electroless plating apparatus, immersing the basket jig for the electroless plating apparatus into a plating bath where a plating solution exists, performing a plating on a printed circuit board by immersing all the basket jig for the electroless plating apparatus into the plating solution and extracting the basket jig for the electroless plating apparatus from the plating bath.

In immersing the basket jig for the electroless plating apparatus into the plating bath, a rotation of a basket is generated by generating a difference of buoyancy due to a density difference.

In immersing the basket jig for the electroless plating apparatus into the plating bath, a top position and a bottom position of a basket are in reverse.

In immersing the basket jig for the electroless plating apparatus into the plating bath, a rotation of the basket is generated due to a self-weight generated since the buoyancy becomes smaller.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the present general inventive concept will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIGS. 1 to 3 and 4A-4B are perspective views showing a basket jig for an electroless plating apparatus in accordance with an embodiment of the present invention; and

FIGS. 5A-5C are a flow chart showing an electroless plating method in accordance with another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERABLE EMBODIMENTS

Embodiments of the present invention to achieve the above-described objects will be described with reference to the accompanying drawings. In this description, the same elements are represented by the same reference numerals, and additional description which is repeated or limits interpretation of the meaning of the invention may be omitted.

The technical constructions as well as the effects thereof for the objects of the basket jig for the electroless plating apparatus and the electroless plating method in accordance with the embodiments of the present invention will be understood clearly with reference to the shown drawings.

Although the singular form is used in this specification, it should be noted that the singular form can be used as the concept representing the plural form unless being contradictory to the concept of the invention or clearly interpreted otherwise. It should be understood that the terms such as “having”, “including”, and “comprising” used herein do not preclude existence or addition of one or more other elements or combination thereof.

FIG. 1 a is a perspective view of the basket jig for an electroless plating apparatus in accordance with the embodiment of the present invention.

As shown, the basket jig 100 for the electroless plating apparatus in accordance with the present invention includes a basket 110 provided with a plurality of printed circuit boards 111, a rotating structure 120 coupled to top portions of both sides of the basket 100 and a tube in a shape of a rectangular plate coupled to bottom portion of the basket.

At this time, the rotating structure 120 may be formed of a carrier 123, a bearing 12 placed on a bottom portion of the carrier 123 and a rotating axis for supporting the basket. The carrier 123 corresponds to a connection member to move the basket jig 100 for the electroless plating apparatus up and down and the bearing 122 is a joint member to connect the rotating axis 121 connected to the basket 110 with the carrier 123 as well as to play a role of rotating the basket 110 back and forth at the same time. The carrier 123 may include an elevating unit (not shown in drawings) to control the elevation between the position of depositing into a plating solution 141 in a plating bath 140 and the position of extracting on the plating bath 140. Since the elevating unit may be used as a conventional unit, it is not described in detail in the present specification.

Although the rotating axis 121 may be placed on a top portion with respect to the center of the basket 110, since the rotating axis 121 is coupled to the basket for guide the rotation of the basket 110, the object of the present invention can be achieved even if the rotating axis 121 is coupled to the upper most portion of the basket.

And also, since the basket 110 is constructed to have a rectangular frame shape by connecting vertical and horizontal frames and a plurality of fixed clamps are arranged at top and bottom intervals so as to fix the printed circuit boards 111 inside thereof, when the printed circuit boards 111 are loaded, the printed circuit boards 111 are not in contact with each other and the warping of the printed circuit boards 111 is not generated. At this time, since the left side and the right side of the basket 110 is coupled to the rotating structure 120, it can be constructed in a plate shape so as to fix the basket 110 and the rotating axis 121.

The rotating axis 121 may be further coupled to an apparatus to be driven by an external power device and may be further include a control device (not shown in the drawings) to rotate the basket 110 through the rotating axis.

On the other hands, a tube 130 may be formed of a thermoplastic resin which has an excellent corrosion resistance to prevent it from being corroded from the plating solution 141 and has a density lower than that of the plating solution 141.

And also, as shown in FIG. 2, the basket 110 may be divided so as to be formed of materials having densities different from each other for forming a difference of buoyancy to be generated at a bottom of the basket 110. For example, a front part and a rear part of the tube 130 are divided and constructed with materials having densities different from each other, and the sizes of buoyancies of places where each material is placed are generated differentially. At this time, since the sizes of the buoyancies generated at the bottom part of the basket 110 are formed differentially so as to rotate the basket 110 up and down, it may be preferable that they are arranged at a front and a rear places with reference to a front surface. Since the rotation direction of the basket 110 is not an important factor to effect on the plating process, the materials having densities different from each other may not be fixed on the front part and the rear part, accordingly, it can be constructed only anyone of the divided parts.

And also, as shown in FIG. 3, a side part of the tube 130 may be a trapezoid shape having a front part and a rear part of a height lower than that of the front part. Although the tube 130 is formed with a material of a uniform density, since different buoyancies are formed due to the different sizes of the buoyancies according to the positions, the basket 110 can be rotated inside of the plating solution 141 if it is interlocked with the rotating structure 120 coupled thereto the rotating axis 121. At this time, since, in order to form the difference of buoyancy formed back and forth of the tube 131, the height of the front part is fixed and the height of the rear part can be varied and the influence exerting on the rotation of the basket 110 by the buoyancy may be varied in comparison with the type of the substrate, the size of the basket jig and the gravity occupied by the other equipment, the height of the rear part may be determined experimentally; and, in order to maximize the difference of the buoyancy sizes exerting on the front part and the rear part, it is preferable that the height of the rear part is set as 0, that is, the shape of the side part becomes a right rectangle shape.

And also, as shown in FIG. 4, the tube 132 coupled to the bottom of the basket 110 is arranged in such a way that the patterns are formed on a front part of the basket 110, and may be coupled in such a way that the patterns are separated at a predetermined interval. When the basket 110 loaded therein the printed circuit boards 111 is deposited into the plating solution 141 or extracted from the plating solution 141, since the buoyancies are generated differentially according to the positions in the tube 132 where the patterns are coupled to the bottom of the basket, although the tube 132 formed thereon the patterns is coupled to the bottom part of the basket 110, the rotation of the basket 110 may be induced when the basket 110 loaded therein the printed circuit boards 111 is deposited into the plating solution 141 or extracted from the plating solution 141.

On the other hands, the materials forming the tube 130 may be any one selected from a group consisting of polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), polypropylene, fiberglass-reinforced plastics, poluethylene, furan, epoxy, polyester, vinyl ester, urethane, natural rubber, neporpene, butyl rubber, chlorobutyl rubber, chlorosulfonated polyethylenen (CSPE), fluorocarbons or the like.

For reference, the buoyancy F in the fluid may be calculated through the following mathematical equation 1.

F=m×g=ρ×V×g  Equ. 1

Wherein, F is a size of buoyancy received by the fluid;

m is a mass of the fluid occupied by a sunken portion;

g is an acceleration of gravity;

ρ is a density of fluid; and

V is a volume of the sunken portion.

In case when the time to be consumed for rotating the basket 110 when being deposited into the plating solution 141 or extracting from the plating solution occupies a high ratio in comparison with a total plating time, it becomes a factor to generate the deviation of plating; and, in case when it occupies a low ratio, a contact between adjacent printed circuit boards may be generated or warpage of each printed circuit board may be generated. Accordingly, the prior art to determine the buoyancy that the basket jig for an electroless plating apparatus including the basket 110 loaded therein the printed circuit boards 111 can be received in the fluid and the gravity exerting on the basket jig for an electroless plating apparatus synthetically may be an appropriate reference to select the type or material of the tube 130 to be coupled to a bottom of the basket 110 loaded thereon the printed circuit boards 111.

FIG. 5 is a flow chart schematically showing an electroless plating method of printed circuit boards in accordance with another embodiment of the present invention.

At first, referring to FIG. 5, after the printed circuit boards 111 to be a target of the plating is fixed to the basket 110 by a clamp, the plating solution 141 is inserted into the plating bath 140 and the basket jig 100 for the electroless plating is positioned on the plating bath 140. If the basket jig 100 for the electroless plating is deposited in the plating bath 140 slowly, the buoyancy is generated upward from the moment when the tube 130 couple to the bottom of the basket 110 is immerged into the plating solution and the slope can be formed back or forth due to the differential buoyancy.

At this time, although the basket 110 can be rotated due to the characteristics of the bearing 122 as a connecting member to connect the rotating axis 121 with the carrier 123 during the process of depositing, since the elevating part coupled to the carrier 123 exerts an external force under the plating solution 141, the basket 110 cannot elevate to the surface of the plating solution 141 although it can be rotated by receiving the buoyancy.

Thereafter, referring to FIG. 5 b, in case when the basket 110 is completely deposited into the plating solution 141, the top and bottom positions are inverted in comparison with the state before the basket 110 is deposited into the plating solution 141.

At this time, the tube 130 coupled to the bottom part of the basket 110 is positioned at a top of the plating solution 141 by being turned up and down, since the rotating axis 121 is placed at a bottom part at a center of the basket 110, although receiving the gravity to restore to an original place, since it is a very small force in comparison with the buoyancy and the rotating axis 121 coupled to the basket 110 is fixed to the carrier, the basket 110 may be maintained at the up and down inverted state in the plating solution 141.

And, since the process is a step of plating the printed circuit boards 111, in order to reduce the deviation of plating, those skilled in the art can use the known devices such as an air bubble emitting device of an air pipe structure, a rotating device to stirring the plating solution or the like.

And then, referring to FIG. 5 c, if the plating process is finished, the basket 110 is moved upward with moving the carrier 123 upward. At this time, if the basket 110 is extracted from the plating solution 141, the volume occupied by the basket 110 in the fluid is reduced to thereby reducing the buoyancy and the constant gravity is relatively increased. Accordingly, since the rotating axis 121 coupled to the side part of the basket 110 is moved downward with respect to the center of gravity (the state that the top and bottom of the basket are inverted), the basket 110 loaded therein the plurality of printed circuit board 111 can generate the rotation force according to the self-weight in order to restore the original place.

As described above, a basket jig for an electroless plating apparatus and an electroless plating method in accordance with the present invention can prevent the omission of plating by rotating so as to change the top and the bottom position two times when the basket provided with the printed circuit board is inserted and extracted in case when the printed circuit board is a thin film ranging from 0.1 μm to 1 μm; since the deviation of the plating thickness according to the top and the bottom positions of the printed circuit board immerged into the plating solution can be minimized, the uniformity of the plating film can be secured; and the printed circuit board having excellent quality and high reliability can be obtained by minimizing the thickness deviation.

And also, the present invention has an advantage financially since the plating equipment construction is simple and it has to spare in securing the installation space by supplying a simple jig for an electroless plating.

The above-described embodiments and the accompanying drawings are provided as examples to help understanding of those skilled in the art, not limiting the scope of the present invention. Further, embodiments according to various combinations of the above-described components will be apparently implemented from the foregoing specific descriptions by those skilled in the art. Therefore, the various embodiments of the present invention may be embodied in different forms in a range without departing from the essential concept of the present invention, and the scope of the present invention should be interpreted from the invention defined in the claims. It is to be understood that the present invention includes various modifications, substitutions, and equivalents by those skilled in the art. 

What is claimed is:
 1. A basket jig for an electroless plating apparatus comprising: a basket loaded thereon a plurality of printed circuit boards; a rotating structure coupled to top portions of both sides of the basket; and a tube in a shape of a rectangular plate coupled to bottom portions of the basket.
 2. The basket jig for an electroless plating apparatus according to claim 1, wherein the rotating structure includes a carrier to move up and down, a bearing placed in a bottom portion and a rotating axis coupled to the bearing of which end portions are connected to the basket.
 3. The basket jig for an electroless plating apparatus according to claim 2, wherein the tube is divided in such a way that materials having different densities from each other are arranged on a front part and a rear part.
 4. The basket jig for an electroless plating apparatus according to claim 2, wherein the tube has a side surface in a shape of a trapezoid or a triangle as a structure to have a long front part and a short rear part.
 5. The basket jig for an electroless plating apparatus according to claim 2, wherein a point is formed on the tube to be separated from a bottom front part of the basket at a predetermined interval.
 6. The basket jig for an electroless plating apparatus according to one of claims 1 to 5, wherein the tube is made of a corrosion resistant material capable of protecting the corrosion from a plating solution.
 7. The basket jig for an electroless plating apparatus according to claim 6, wherein the tube is made of a material with a density lower than that of the plating solution.
 8. The basket jig for an electroless plating apparatus according to claim 7, wherein the tube is made of a material selected from a group consisting of polytetrafluoreethylene (PTFE), polyvinyl chloride (PVC), polypropylene, fiberglass-reinforced plastics, polyethylene, furan, epoxy, polyester, vinyl ester, urethane, natural rubber, neporpene, butyl rubber, chlorobutyl rubber, chlorosulfonated polyethylene (CSPE), fluororcarbons or the like.
 9. An electroless plating method comprising: placing a basket jig for an electroless plating apparatus; immersing the basket jig for the electroless plating apparatus into a plating bath where a plating solution exists; performing a plating on a printed circuit board by immersing all the basket jig for the electroless plating apparatus into the plating solution; and extracting the basket jig for the electroless plating apparatus from the plating bath.
 10. The electroless plating method according to claim 9, wherein, in immersing the basket jig for the electroless plating apparatus into the plating bath, a rotation of a basket is generated by generating a difference of buoyancy due to a density difference.
 11. The electroless plating method according to claim 9, wherein, in immersing the basket jig for the electroless plating apparatus into the plating bath, a top position and a bottom position of a basket are in reverse.
 12. The electroless plating method according to claim 9, wherein, in immersing the basket jig for the electroless plating apparatus into the plating bath, a rotation of the basket is generated due to a self-weight generated since the buoyancy becomes smaller. 